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  <div class="section" id="module-ensurepip">
<span id="ensurepip-bootstrapping-the-pip-installer"></span><h1>28.2. <a class="reference internal" href="#module-ensurepip" title="ensurepip: Bootstrapping the &quot;pip&quot; installer into an existing Python installation or virtual environment."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ensurepip</span></code></a> --- Bootstrapping the <code class="docutils literal notranslate"><span class="pre">pip</span></code> installer<a class="headerlink" href="#module-ensurepip" title="永久链接至标题">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified">3.4 新版功能.</span></p>
</div>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-ensurepip" title="ensurepip: Bootstrapping the &quot;pip&quot; installer into an existing Python installation or virtual environment."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ensurepip</span></code></a> package provides support for bootstrapping the <code class="docutils literal notranslate"><span class="pre">pip</span></code>
installer into an existing Python installation or virtual environment. This
bootstrapping approach reflects the fact that <code class="docutils literal notranslate"><span class="pre">pip</span></code> is an independent
project with its own release cycle, and the latest available stable version
is bundled with maintenance and feature releases of the CPython reference
interpreter.</p>
<p>In most cases, end users of Python shouldn't need to invoke this module
directly (as <code class="docutils literal notranslate"><span class="pre">pip</span></code> should be bootstrapped by default), but it may be
needed if installing <code class="docutils literal notranslate"><span class="pre">pip</span></code> was skipped when installing Python (or
when creating a virtual environment) or after explicitly uninstalling
<code class="docutils literal notranslate"><span class="pre">pip</span></code>.</p>
<div class="admonition note">
<p class="first admonition-title">注解</p>
<p class="last">This module <em>does not</em> access the internet. All of the components
needed to bootstrap <code class="docutils literal notranslate"><span class="pre">pip</span></code> are included as internal parts of the
package.</p>
</div>
<div class="admonition seealso">
<p class="first admonition-title">参见</p>
<dl class="last docutils">
<dt><a class="reference internal" href="../installing/index.html#installing-index"><span class="std std-ref">Installing Python Modules</span></a></dt>
<dd>The end user guide for installing Python packages</dd>
<dt><span class="target" id="index-0"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0453"><strong>PEP 453</strong></a>: Explicit bootstrapping of pip in Python installations</dt>
<dd>The original rationale and specification for this module.</dd>
</dl>
</div>
<div class="section" id="command-line-interface">
<h2>28.2.1. Command line interface<a class="headerlink" href="#command-line-interface" title="永久链接至标题">¶</a></h2>
<p>The command line interface is invoked using the interpreter's <code class="docutils literal notranslate"><span class="pre">-m</span></code> switch.</p>
<p>The simplest possible invocation is:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">ensurepip</span>
</pre></div>
</div>
<p>This invocation will install <code class="docutils literal notranslate"><span class="pre">pip</span></code> if it is not already installed,
but otherwise does nothing. To ensure the installed version of <code class="docutils literal notranslate"><span class="pre">pip</span></code>
is at least as recent as the one bundled with <code class="docutils literal notranslate"><span class="pre">ensurepip</span></code>, pass the
<code class="docutils literal notranslate"><span class="pre">--upgrade</span></code> option:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">python</span> <span class="o">-</span><span class="n">m</span> <span class="n">ensurepip</span> <span class="o">--</span><span class="n">upgrade</span>
</pre></div>
</div>
<p>By default, <code class="docutils literal notranslate"><span class="pre">pip</span></code> is installed into the current virtual environment
(if one is active) or into the system site packages (if there is no
active virtual environment). The installation location can be controlled
through two additional command line options:</p>
<ul class="simple">
<li><code class="docutils literal notranslate"><span class="pre">--root</span> <span class="pre">&lt;dir&gt;</span></code>: Installs <code class="docutils literal notranslate"><span class="pre">pip</span></code> relative to the given root directory
rather than the root of the currently active virtual environment (if any)
or the default root for the current Python installation.</li>
<li><code class="docutils literal notranslate"><span class="pre">--user</span></code>: Installs <code class="docutils literal notranslate"><span class="pre">pip</span></code> into the user site packages directory rather
than globally for the current Python installation (this option is not
permitted inside an active virtual environment).</li>
</ul>
<p>By default, the scripts <code class="docutils literal notranslate"><span class="pre">pipX</span></code> and <code class="docutils literal notranslate"><span class="pre">pipX.Y</span></code> will be installed (where
X.Y stands for the version of Python used to invoke <code class="docutils literal notranslate"><span class="pre">ensurepip</span></code>). The
scripts installed can be controlled through two additional command line
options:</p>
<ul class="simple">
<li><code class="docutils literal notranslate"><span class="pre">--altinstall</span></code>: if an alternate installation is requested, the <code class="docutils literal notranslate"><span class="pre">pipX</span></code>
script will <em>not</em> be installed.</li>
<li><dl class="first docutils">
<dt><code class="docutils literal notranslate"><span class="pre">--default-pip</span></code>: if a &quot;default pip&quot; installation is requested, the</dt>
<dd><code class="docutils literal notranslate"><span class="pre">pip</span></code> script will be installed in addition to the two regular scripts.</dd>
</dl>
</li>
</ul>
<p>Providing both of the script selection options will trigger an exception.</p>
<div class="versionchanged">
<p><span class="versionmodified">在 3.6.3 版更改: </span>The exit status is non-zero if the command fails.</p>
</div>
</div>
<div class="section" id="module-api">
<h2>28.2.2. Module API<a class="headerlink" href="#module-api" title="永久链接至标题">¶</a></h2>
<p><a class="reference internal" href="#module-ensurepip" title="ensurepip: Bootstrapping the &quot;pip&quot; installer into an existing Python installation or virtual environment."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ensurepip</span></code></a> exposes two functions for programmatic use:</p>
<dl class="function">
<dt id="ensurepip.version">
<code class="descclassname">ensurepip.</code><code class="descname">version</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ensurepip.version" title="永久链接至目标">¶</a></dt>
<dd><p>Returns a string specifying the bundled version of pip that will be
installed when bootstrapping an environment.</p>
</dd></dl>

<dl class="function">
<dt id="ensurepip.bootstrap">
<code class="descclassname">ensurepip.</code><code class="descname">bootstrap</code><span class="sig-paren">(</span><em>root=None</em>, <em>upgrade=False</em>, <em>user=False</em>, <em>altinstall=False</em>, <em>default_pip=False</em>, <em>verbosity=0</em><span class="sig-paren">)</span><a class="headerlink" href="#ensurepip.bootstrap" title="永久链接至目标">¶</a></dt>
<dd><p>Bootstraps <code class="docutils literal notranslate"><span class="pre">pip</span></code> into the current or designated environment.</p>
<p><em>root</em> specifies an alternative root directory to install relative to.
If <em>root</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, then installation uses the default install location
for the current environment.</p>
<p><em>upgrade</em> indicates whether or not to upgrade an existing installation
of an earlier version of <code class="docutils literal notranslate"><span class="pre">pip</span></code> to the bundled version.</p>
<p><em>user</em> indicates whether to use the user scheme rather than installing
globally.</p>
<p>By default, the scripts <code class="docutils literal notranslate"><span class="pre">pipX</span></code> and <code class="docutils literal notranslate"><span class="pre">pipX.Y</span></code> will be installed (where
X.Y stands for the current version of Python).</p>
<p>If <em>altinstall</em> is set, then <code class="docutils literal notranslate"><span class="pre">pipX</span></code> will <em>not</em> be installed.</p>
<p>If <em>default_pip</em> is set, then <code class="docutils literal notranslate"><span class="pre">pip</span></code> will be installed in addition to
the two regular scripts.</p>
<p>Setting both <em>altinstall</em> and <em>default_pip</em> will trigger
<a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>.</p>
<p><em>verbosity</em> controls the level of output to <a class="reference internal" href="sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a> from the
bootstrapping operation.</p>
<div class="admonition note">
<p class="first admonition-title">注解</p>
<p class="last">The bootstrapping process has side effects on both <code class="docutils literal notranslate"><span class="pre">sys.path</span></code> and
<code class="docutils literal notranslate"><span class="pre">os.environ</span></code>. Invoking the command line interface in a subprocess
instead allows these side effects to be avoided.</p>
</div>
<div class="admonition note">
<p class="first admonition-title">注解</p>
<p class="last">The bootstrapping process may install additional modules required by
<code class="docutils literal notranslate"><span class="pre">pip</span></code>, but other software should not assume those dependencies will
always be present by default (as the dependencies may be removed in a
future version of <code class="docutils literal notranslate"><span class="pre">pip</span></code>).</p>
</div>
</dd></dl>

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<li><a class="reference internal" href="#command-line-interface">28.2.1. Command line interface</a></li>
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